Pick-up for scanning a sound groove for two-coordinate recording



Dec. 10, 1963 I H. ZIMMERMANN ETAL 3,113,783 PICK-UP F R SCANNING A SOUND GROOVE FOR TWO-COORDINATE RECORDING Filed Aug. 10, 1962 W n/r095:

HEINRICH ZTMMERMAN'N and LUKAS SCHWER United States Patent 3,113,783 PICK-UP FDR SCANNENG A SU UND GROGVE FGR TWO -TIQQRDTNATE RECQRDTNG Heinrich Zimmermann and Lukas Schvver, Saniat Geergen, Black Forest, Germany, assignors to @sirar Steidinger and Siegfried Steidinger, Sanlrt Georgen, Black Forest, Germany Filed Aug. 10, 1962, Ser. No. 216,246 2 (Jlaims. (Ci. 2'7437) The present invention concerns a pick-up for scanning a sound groove for two-coordinate recording, the scanning needle of which is connected to each of the electromagnetic transducers associated with the two coordinates by means of a coupling member in the form of a web or strap which is adapted to transmit pressure forces substantially only in its longitudinal direction for the purpose of producing a voltage and to yield resiliently but only at right angles thereto.

It has already been proposed to arrange a strap between the scanning needle and the transducer concerned, which strap tapers at its ends to facilitate deformation. If such a strap is made of metal it is not possible for the links to be made so thin in consideration of the practical manipulation of the pick-up, that on the one hand there can be obtained a sufficiently easy deflection or small return force and a satisfactory uncoupling of the transducer on the other hand.

A pick-up is known moreover wherein the coupling straps are made of rubber-like elastic material. This in fact permits a pick-up to be constructed in practice having a satisfactorily ready deflection of the webs or straps. The rubber-like elastic property of the material however necessitates a comparatively large cross-section of the webs, as these are subjected to buckling stress. Compared with metal webs this results in a large inert mass, since the specific gravities, for example, of rubber and light metal are not so far different from one another as are their elasticities decisive for the buckling resistance.

Experience has shown that most piezo-electric pickups, and thus not only for two-component recording, have an interfering resonance in the region of about 5-8 kHz. Investigations have shown that this resonance occurs with certainty above all in pick-ups which are equipped with rubber-like elastic coupling webs. Further investigations have shown that these coupling webs carry out natural vibrations in this frequency range. Apart from the resonance phenomenon in the frequency course of the pick-up the uncoupling effect of the webs is considerably reduced in the resonance region, which results in a reduction of the effect in stereophonic transmission.

According to the present invention the disadvantages of known pick-ups are removed by the fact that the weblike coupling member is composed of a web part and link part, the web part being of a material which relative to the deformation forces occurring during scanning is practically rigid, and the link part consists of a rubberlike elastic material.

The expedient development of the invention consists in that the web-like coupling members are U-shaped, adapted to be inserted with one limb in a rubber-like elastic part connected to the scanning needle and with the other limb in a rubber-like elastic part connected to the transducer concerned.

3,113,783 Patented Dec. 10, 1963 By this arrangement the webs receive in a simple manner a comparatively great resistance force vertically to the plane in which they move when carrying out their coupling function. 1

The invention will be described further, by way of example, with reference to the accompanying drawing in which the single FIGURE shows a piezoelectric pick-up without housing.

Two piezoelectric transducers 1, 2 which are cut as torsion plates, are clamped at one edge '3, 4 in the housing. A rubber part 7 enclosing the two opposite edges 5, 6 anchors one corner of the edges 5, 6 articulately to the housing, in that by means of a wedge-shaped extension 8 it is mounted in the housing. The rubber part 7 is extended at the other corners of the edges 5, 6 of the transducers 1, 2 and each contain an aperture 9, 10 in each of which one of the two U-shaped web parts 11, 12 made of light metal are inserted with one of its limbs. The two other limbs are inserted in the same manner in one common rubber part 13. Both limbs for the purpose of a secure seating are conically enlarged towards their ends. The limbs mounted in the rubber part 13 have an angular profile 14, 15 to increase the stability of the coupling mechanism and its damping effect. A needle carrier 16 is mounted at one end 17 on the housing and in the proximity of the other end the ends carrying the scanning tip 18 coupled to the rubber part 13.

The pick-up is intended for a modulation direction of the sound groove of relative to the vertical. The two web parts 11, 12 are arranged in this direction. Each strap in accordance with the arrangement shown, when the scanning 18 tip is deflected, transmits only in this direction a movement to the transducer 1, 2 connected therewith. Any movements at right angles thereto cause the limbs of the U-shaped web parts 11, L2 to be twisted in their mountings.

In place of piezo-electric transducers it is of course also possible to drive, for example, pole armatures or coils.

We claim:

1. A pick-up including two electromechanical transducers with rubber-like elastic coupling parts near their driving positions, a scanning needle connected with a rubber-like elastic coupling part, two webs comprised of material practically rigid relative to the deformation forces arising during scanning, each embedded with its end in the rubber-like elastic coupling part of one transducer and with the other end in the rubber-like elastic coupling part connected to the scanning needle, the direction of the webs being selected in each case corresponding approximately to the two modulation directions to be scanned with the pick-up.

2. A pick-up according to claim 1 having straps bent over at right angles at the ends, the ends bent at right angles of which each being embedded in rubber-like elastic coupling parts.

References Cited in the file of this patent UNITED STATES PATENTS 3,026,382 Lalesse Mar. 20, 1962 3,054,862 Hammond Sept. 18, 1962 3,060,280 Wood Oct. 23, 1962 FOREIGN PATENTS 863,889 Great Britain Mar. 29, 1961 Notice of Adverse Decision in Interference In Interference No. 95,010 involving Patent No. 3,113,783, II. Zimmernmnn and L. Schwer, PICK-UP FOR SCANNING A SOUND GROOVE FOR TW'O-COORDINATE RECORDING, final judgment adverse to the patentees was rendered Apr. 25, 1969, as to claim 1.

[Ofiicz'al Gazette January 13, 1970.] 

1. A PICK-UP INCLUDING TWO ELECTROMECHANICAL TRANSDUCERS WITH RUBBER-LIKE ELASTIC COUPLING PARTS NEAR THEIR DRIVING POSITIONS, A SCANNING NEEDLE CONNECTED WITH A RUBBER-LIKE ELASTIC COUPLING PART, TWO WEBS COMPRISED OF MATERIAL PRACTICALLY RIGID RELATIVE TO THE DEFORMATION FORCES ARISING DURING SCANNING, EACH EMBEDDED WITH ITS END IN THE RUBBER-LIKE ELASTIC COUPLING PART OF ONE TRANSDUCER AND WITH THE OTHER END IN THE RUBBER-LIKE ELASTIC COUPLING PART CONNECTED TO THE SCANNING NEEDLE, THE DIRECTION OF THE 